In this paper, the idea of square fractal geometry has been utilized to introduce a tunable wideband graphene-based perfect plasmonic absorber in the near-infrared region. It consists of a MgF₂ layer and an array of gold squares fractal loaded on a graphene layer. In the designed absorber a single layer of graphene has been used instead of multilayered graphene structures. The structure is polarization-insensitive under normal incidence due to the geometric symmetry. The absorption and bandwidth of the structure are almost insensitive to the incident angle up to 15° and 45° for TE and TM polarizations, respectively. Moreover, by choosing appropriate structural parameters, the resonance wavelength of the desired plasmonic absorber can be controlled. The absorption of the introduced structure can be tuned by changing the chemical potential of the graphene. Therefore, the proposed fractal absorber can act as switch and inverter at λ = 1995 nm. Furthermore, the equivalent circuit model of the absorber has been derived to confirm the validity of the simulation results. The superiorities of our fractal absorber are wide full-width at half-maximum of 406 nm, multi-applicant, perfect absorption, and fabrication feasibility due to the simple structure with the maximum absorption tolerance error of 5.12%.

在本文中，正方形分形几何的思想已被用于在近红外区域引入可调谐宽带基于石墨烯的理想等离激元吸收器。它由MgF _2组成石墨烯层和金正方形分形的阵列加载到石墨烯层上。在设计的吸收器中，已使用单层石墨烯代替了多层石墨烯结构。由于几何对称性，该结构在法向入射下对偏振不敏感。对于TE和TM偏振，该结构的吸收率和带宽几乎分别对入射角高达15°和45°不敏感。而且，通过选择适当的结构参数，可以控制所需的等离子体吸收器的共振波长。可以通过改变石墨烯的化学势来调节引入结构的吸收率。因此，所提出的分形吸收器可以作为λ处的开关和反相器 = 1995纳米。此外，推导了吸收器的等效电路模型，以确认仿真结果的有效性。我们的分形吸收器的优势在于其最大半峰宽为406 nm，具有多种应用，完美的吸收性，并且由于结构简单，最大吸收容差误差为5.12％而具有制造可行性。